In a 5-4 decision authored by Justice Kennedy, the Court held in Windsor v. United States that section 3 of the Federal Defense of Marriage Act (DOMA) is unconstitutional. Advocates had attacked section 3 on two primary grounds. The principal argument leveled at section 3 was that it violated principles of equal protection by denying one class of married spouses — lesbian and gay spouses — all federal marital benefits.

Section 3 was also attacked on a number of federalism-based grounds. Some advocates pushed a particularly strong federalism variant, arguing that DOMA was unconstitutional because Congress lacked the authority to define or determine family status. I call this the categorical family status federalism argument. Others endorsed a more moderated claim. Under this theory, the fact that a law — here section 3 of DOMA — deviated from the historic allocation of power as between the federal government and the states was simply a basis for applying a more careful level of equal protection scrutiny. Under this theory, the federalism-based concerns were not an independent basis for striking down the law.

This Essay argues that civil rights advocates dodged a bullet when the Windsor Court declined to embrace the categorical family status federalism theory. While its acceptance would have brought along the short-term gain of providing a basis for invalidating DOMA, it also would have curtailed the ability of federal officials to protect same-sex couples and other families.